1. Field of the Invention
This invention relates to high pressure fluid injection systems and, more particularly, to fluid injection connectors for a high pressure fluid manifold.
2. Description of Related Art
Fluid injection systems are evolving to provide greater flexibility and efficiency in both their application and operation. In recent years, the fuel systems industry has focused attention on the development of energy accumulating, nozzle controlled, fuel system concepts that provide engine speed and load independent control over injection timing, pressure, quantity and multiple pulse rate shape. This attention has led to the commercialization of several concepts packaged in the form of a fluid pressurizing pump connected to a hydraulic energy storage device or high-pressure common rail connected to one or more electrically operable injector nozzles. The common rail portion of these systems is called upon to conform to the physical arrangement of pumps, injectors, and other engine structures, to withstand dynamic thermal forces and, hydraulic forces, and to transfer pressurized fluid. Conventional common rails have had to be substantially robust and very stiff, forged steel rails in order to withstand the rigors of high performance operation.
Embodiments of the invention provide a modular, structurally flexible and compact fluid manifold branch connector that meets the needs of existing and future energy accumulating, nozzle controlled fluid systems without sacrificing cost effectiveness and reliability in serving a basic function to contain and transfer high-pressure fluid. Embodiments of the invention combine commercially available tubing and termination fittings with readily manufactured, mid-run, three-way connectors of a unique stress reducing design to form a connector assembly.
An exemplary embodiment of the invention has a connection that permits the use of substantially inexpensive tubing, rather than the conventionally required forged rail to supply fluid to the injectors. The tubing of the exemplary embodiment is much more flexible than the conventional forged rail and can adapt much more easily to the assembly forces, vibrational forces, thermal forces and hydraulic forces than the conventional forged rail.
The exemplary embodiment includes a symmetric tube collar through which the fluid supply tube passes. The symmetric tube collar axially surrounds the fluid supply tube and is adapted to relieve the stresses placed upon the tubing by the high pressures of the fluid. The tube collar seals to the tubing using a braze joint that operates in compression rather than in shear as conventional connectors have operated. The brazing is placed into compression by the high pressure fluid pushing outwardly on the tube walls and pushing the tube walls into contact with the tube collar. Placing the brazing into compression provides a much more reliable seal when compared to conventional braze seals which rely upon shear stress resistance.
The exemplary embodiment also includes a unique dynamic seal ring that connects the fluid injector to the tube collar. The dynamic seal ring includes a unique xe2x80x9cCxe2x80x9d shaped cross-section that enables the high pressure fluid to act to expand the seal into intimate contact with both the injector and the tube collar. The ability of the seal to adapt to the surfaces of the injector and the tube collar enable the use of parts that have larger manufacturing tolerances than have conventionally been required. The seal also substantially eliminates a fretting mode of failure that is commonly experienced with dynamically loaded, high-pressure seals. Additionally, the seal can be manufactured at a low cost and in a variety of sizes and shapes to suit specific applications.
The tube collar of the exemplary embodiment also includes an annular cavity that surrounds a hole that is cross-drilled through the tube. The tube collar also includes an exit bore that provides fluid communication between the annular cavity and a fluid injector connected to the tube collar. The annular cavity of the exemplary tube collar is wider than the hole cross-drilled in the tube and makes it much easier to align the hole in the tube with the cavity than in conventional designs. Additionally, the annular cavity acts as a stress reliever because the inside wall and outside wall of the tube adjacent the cross-drilled hole experience the same hydraulic pressure.
The cross-drilled hole through the tube of the exemplary embodiment is oriented substantially perpendicularly to the exit bore of the annular cavity of the tube collar of the exemplary embodiment. This orientation minimizes bending stresses across the cross-drilled hole because the hole is aligned substantially perpendicularly to the axis through which the major vibrational forces are transmitted. Additionally, the cross-drilled hole of the exemplary embodiment is also positioned just below the longitudinal axis of the tube to substantially correspond to the neutral bending axis of the tube. Also, since the cross-drilled hole of the exemplary embodiment passes entirely through both sides of the tube, the size of each hole may be reduced while still maintaining the flow rate of a single much larger hole.